The use of reciprocating saws that are hand manipulated has simplified the work of both the professional carpenter and the handy homeowner. Such saws are portable and easily manipulated in many work situations. However, most of the blades on the market are not easily manipulated in situations wherein there is need to cut into a corner where the planes of two boards meet at a 90.degree. angle. Furthermore, most blades are not appropriate for starting a cut lying wholly in the plane of the material. While there have previously been disclosed "self-starting" blades, most such blades are special purpose blades that are too fragile or specialized for general use. Finally, many of the blades on the market are made of material of such hardness that they can not be sharpened with the files usually used by carpenters. For example, some of the blades on the market are flame or electro hardened to attain a hardness of about 60 to 62 on the Rockwell scale. Since that is about the hardness of files, such blades are not readily sharpened during the course of use.
There have been blades previously disclosed as self-starting having curved or non-parallel edges. U.S. Pat. No. 3,680,610 to Lindgren describes a blade with two cutting edges for plunging into a planar surface. The blade has oppositely disposed cutting edges. U.S. Pat. No. 3,477,479 to Doty describes a blade having a curved end to enable self-starting of the cut in a planar surface. The non-cutting edge is not parallel to the axis of the blade. The blade is not useful for cutting into corners where two planar surfaces meet at a 90.degree. angle.